Method and apparatus for configuring cell in wireless communication system

ABSTRACT

A method and apparatus for configuring a cell in a wireless communication system is provided. A user equipment (UE) receives a radio resource control (RRC) message which includes a configuration for a secondary cell (SCell) and an indication of an initial state of the SCell. The initial state of the SCell is set to either one of an activated state and deactivated state. The UE configures the SCell based on the configuration and the initial state of the SCell.

This application is a Continuation of U.S. patent application Ser. No.15/943,344, filed Apr. 2, 2018, which is a Continuation of U.S. patentapplication Ser. No. 14/650,750, filed Jun. 9, 2015, now U.S. Pat. No.9,936,527, which is a 35 USC § 371 National Stage entry of InternationalApplication No. PCT/KR2014/000429, filed Jan. 15, 2014, and claimspriority to U.S. Provisional Application No. 61/753,388, filed Jan. 16,2013, all of which are hereby incorporated by reference in theirentireties as if fully set forth herein.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to wireless communications, and morespecifically, to a method and apparatus for configuring a cell in awireless communication system.

Related Art

Universal mobile telecommunications system (UMTS) is a 3^(rd) generation(3G) asynchronous mobile communication system operating in wideband codedivision multiple access (WCDMA) based on European systems, globalsystem for mobile communications (GSM) and general packet radio services(GPRS). A long-term evolution (LTE) of UMTS is under discussion by the3^(rd) generation partnership project (3GPP) that standardized UMTS.

The 3GPP LTE is a technology for enabling high-speed packetcommunications. Many schemes have been proposed for the LTE objectiveincluding those that aim to reduce user and provider costs, improveservice quality, and expand and improve coverage and system capacity.The 3GPP LTE requires reduced cost per bit, increased serviceavailability, flexible use of a frequency band, a simple structure, anopen interface, and adequate power consumption of a terminal as anupper-level requirement.

Carrier aggregation (CA) may be introduced. In CA, two or more componentcarriers (CCs) are aggregated in order to support wider transmissionbandwidths up to 100 MHz. A UE may simultaneously receive or transmit onone or multiple CCs depending on its capabilities. A Rel-10 UE withreception and/or transmission capabilities for CA can simultaneouslyreceive and/or transmit on multiple CCs corresponding to multipleserving cells. A Rel-8/9 UE can receive on a single CC and transmit on asingle CC corresponding to one serving cell only.

A cell is combination of downlink resources and optionally uplinkresources. The linking between the carrier frequency of the downlinkresources and the carrier frequency of the uplink resources is indicatedin the system information transmitted on the downlink resources. Aserving cell may consist of one DL CC and one UL CC. Or, a serving cellmay consist of one DL CC only.

There may be a plurality of serving cells, and the plurality of servingcells consists may consist of one primary cell (PCell) and at least onesecondary cell (SCell). A method for configuring a SCell efficiently maybe required.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for configuring acell in a wireless communication system. The present invention providesa method for indicating an initial state of a secondary cell (SCell).The present invention provides a method for configuring a SCell based onan initial state of the SCell.

In an aspect, a method for configuring, by a user equipment (UE), a cellin a wireless communication system is provided. The method includesreceiving a radio resource control (RRC) message which includes aconfiguration for a secondary cell (SCell) and an indication of aninitial state of the SCell, and configuring the SCell based on theconfiguration and the initial state of the SCell. The initial state ofthe SCell is set to either one of an activated state and deactivatedstate.

The method may further include transmitting or receiving data on theSCell without an additional activation command if the initial state ofthe SCell is set to the activated state.

The method may further include receiving an activation command for theSCell if the initial state of the SCell is set to the deactivated state.

The method may further include activating the SCell according to theactivation command, and transmitting or receiving data on the SCell.

The indication may be received via an RRC connection reconfigurationmessage.

The indication may be defined per UE or per cell.

In another aspect, a user equipment (UE) in a wireless communicationsystem is provided. The UE includes a radio frequency (RF) unit fortransmitting or receiving a radio signal, and a processor coupled to theRF unit, and configured to receive a radio resource control (RRC)message which includes a configuration for a secondary cell (SCell) andan indication of an initial state of the SCell, and configure the SCellbased on the configuration and the initial state of the SCell. Theinitial state of the SCell is set to either one of an activated stateand deactivated state.

An initial state of a SCell can be activated when the SCell is added,and accordingly, data transmission through the SCell can be availablewithout additional an activation procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows LTE system architecture.

FIG. 2 shows a control plane of a radio interface protocol of an LTEsystem.

FIG. 3 shows a user plane of a radio interface protocol of an LTEsystem.

FIG. 4 shows an example of a physical channel structure.

FIG. 5 shows an example of a carrier aggregation of 3GPP LTE-A.

FIG. 6 shows an example of a structure of DL layer 2 when carrieraggregation is used.

FIG. 7 shows an example of a structure of UL layer 2 when carrieraggregation is used.

FIG. 8 shows an example of a potential deployment scenario for CA.

FIG. 9 shows another example of a potential deployment scenario for CA.

FIG. 10 shows another example of a potential deployment scenario for CA.

FIG. 11 shows another example of a potential deployment scenario for CA.

FIG. 12 shows another example of a potential deployment scenario for CA.

FIG. 13 shows an RRC connection reconfiguration procedure.

FIG. 14 shows deployment scenarios of small cells with/without macrocoverage.

FIG. 15 shows an example of dual connectivity to a macro cell and smallcell.

FIG. 16 shows an example of protocol architecture supporting dualconnectivity.

FIG. 17 shows an example of a SCell addition with an indication of aninitial state according to an embodiment of the present invention.

FIG. 18 shows an example of a method for configuring a SCell accordingto an embodiment of the present invention.

FIG. 19 shows a wireless communication system to implement an embodimentof the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The technology described below can be used in various wirelesscommunication systems such as code division multiple access (CDMA),frequency division multiple access (FDMA), time division multiple access(TDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), etc. The CDMA canbe implemented with a radio technology such as universal terrestrialradio access (UTRA) or CDMA-2000. The TDMA can be implemented with aradio technology such as global system for mobile communications(GSM)/general packet ratio service (GPRS)/enhanced data rate for GSMevolution (EDGE). The OFDMA can be implemented with a radio technologysuch as institute of electrical and electronics engineers (IEEE) 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, evolved UTRA (E-UTRA), etc.IEEE 802.16m is evolved from IEEE 802.16e, and provides backwardcompatibility with a system based on the IEEE 802.16e. The UTRA is apart of a universal mobile telecommunication system (UMTS). 3^(rd)generation partnership project (3GPP) long term evolution (LTE) is apart of an evolved UMTS (E-UMTS) using the E-UTRA. The 3GPP LTE uses theOFDMA in a downlink and uses the SC-FDMA in an uplink. LTE-advanced(LTE-A) is an evolution of the LTE.

For clarity, the following description will focus on LTE-A. However,technical features of the present invention are not limited thereto.

FIG. 1 shows LTE system architecture. The communication network iswidely deployed to provide a variety of communication services such asvoice over internet protocol (VoIP) through IMS and packet data.

Referring to FIG. 1, the LTE system architecture includes one or moreuser equipment (UE; 10), an evolved-UMTS terrestrial radio accessnetwork (E-UTRAN) and an evolved packet core (EPC). The UE 10 refers toa communication equipment carried by a user. The UE 10 may be fixed ormobile, and may be referred to as another terminology, such as a mobilestation (MS), a user terminal (UT), a subscriber station (SS), awireless device, etc.

The E-UTRAN includes one or more evolved node-B (eNB) 20, and aplurality of UEs may be located in one cell. The eNB 20 provides an endpoint of a control plane and a user plane to the UE 10. The eNB 20 isgenerally a fixed station that communicates with the UE 10 and may bereferred to as another terminology, such as a base station (BS), a basetransceiver system (BTS), an access point, etc. One eNB 20 may bedeployed per cell. There are one or more cells within the coverage ofthe eNB 20. A single cell is configured to have one of bandwidthsselected from 1.25, 2.5, 5, 10, and 20 MHz, etc., and provides downlinkor uplink transmission services to several UEs. In this case, differentcells can be configured to provide different bandwidths.

Hereinafter, a downlink (DL) denotes communication from the eNB 20 tothe UE 10, and an uplink (UL) denotes communication from the UE 10 tothe eNB 20. In the DL, a transmitter may be a part of the eNB 20, and areceiver may be a part of the UE 10. In the UL, the transmitter may be apart of the UE 10, and the receiver may be a part of the eNB 20.

The EPC includes a mobility management entity (MME) which is in chargeof control plane functions, and a system architecture evolution (SAE)gateway (S-GW) which is in charge of user plane functions. The MME/S-GW30 may be positioned at the end of the network and connected to anexternal network. The MME has UE access information or UE capabilityinformation, and such information may be primarily used in UE mobilitymanagement. The S-GW is a gateway of which an endpoint is an E-UTRAN.The MME/S-GW 30 provides an end point of a session and mobilitymanagement function for the UE 10. The EPC may further include a packetdata network (PDN) gateway (PDN-GW). The PDN-GW is a gateway of which anendpoint is a PDN.

The MME provides various functions including non-access stratum (NAS)signaling to eNBs 20, NAS signaling security, access stratum (AS)security control, Inter core network (CN) node signaling for mobilitybetween 3GPP access networks, idle mode UE reachability (includingcontrol and execution of paging retransmission), tracking area listmanagement (for UE in idle and active mode), P-GW and S-GW selection,MME selection for handovers with MME change, serving GPRS support node(SGSN) selection for handovers to 2G or 3G 3GPP access networks,roaming, authentication, bearer management functions including dedicatedbearer establishment, support for public warning system (PWS) (whichincludes earthquake and tsunami warning system (ETWS) and commercialmobile alert system (CMAS)) message transmission. The S-GW host providesassorted functions including per-user based packet filtering (by e.g.,deep packet inspection), lawful interception, UE Internet protocol (IP)address allocation, transport level packet marking in the DL, UL and DLservice level charging, gating and rate enforcement, DL rate enforcementbased on APN-AMBR. For clarity MME/S-GW 30 will be referred to hereinsimply as a “gateway,” but it is understood that this entity includesboth the MME and S-GW.

Interfaces for transmitting user traffic or control traffic may be used.The UE 10 and the eNB 20 are connected by means of a Uu interface. TheeNBs 20 are interconnected by means of an X2 interface. Neighboring eNBsmay have a meshed network structure that has the X2 interface. The eNBs20 are connected to the EPC by means of an S1 interface. The eNBs 20 areconnected to the MME by means of an S1-MME interface, and are connectedto the S-GW by means of S1-U interface. The S1 interface supports amany-to-many relation between the eNB 20 and the MME/S-GW.

The eNB 20 may perform functions of selection for gateway 30, routingtoward the gateway 30 during a radio resource control (RRC) activation,scheduling and transmitting of paging messages, scheduling andtransmitting of broadcast channel (BCH) information, dynamic allocationof resources to the UEs 10 in both UL and DL, configuration andprovisioning of eNB measurements, radio bearer control, radio admissioncontrol (RAC), and connection mobility control in LTE_ACTIVE state. Inthe EPC, and as noted above, gateway 30 may perform functions of pagingorigination, LTE_IDLE state management, ciphering of the user plane, SAEbearer control, and ciphering and integrity protection of NAS signaling.

FIG. 2 shows a control plane of a radio interface protocol of an LTEsystem. FIG. 3 shows a user plane of a radio interface protocol of anLTE system.

Layers of a radio interface protocol between the UE and the E-UTRAN maybe classified into a first layer (L1), a second layer (L2), and a thirdlayer (L3) based on the lower three layers of the open systeminterconnection (OSI) model that is well-known in the communicationsystem. The radio interface protocol between the UE and the E-UTRAN maybe horizontally divided into a physical layer, a data link layer, and anetwork layer, and may be vertically divided into a control plane(C-plane) which is a protocol stack for control signal transmission anda user plane (U-plane) which is a protocol stack for data informationtransmission. The layers of the radio interface protocol exist in pairsat the UE and the E-UTRAN, and are in charge of data transmission of theUu interface.

A physical (PHY) layer belongs to the L1. The PHY layer provides ahigher layer with an information transfer service through a physicalchannel. The PHY layer is connected to a medium access control (MAC)layer, which is a higher layer of the PHY layer, through a transportchannel. A physical channel is mapped to the transport channel. Data istransferred between the MAC layer and the PHY layer through thetransport channel. Between different PHY layers, i.e., a PHY layer of atransmitter and a PHY layer of a receiver, data is transferred throughthe physical channel using radio resources. The physical channel ismodulated using an orthogonal frequency division multiplexing (OFDM)scheme, and utilizes time and frequency as a radio resource.

The PHY layer uses several physical control channels. A physicaldownlink control channel (PDCCH) reports to a UE about resourceallocation of a paging channel (PCH) and a downlink shared channel(DL-SCH), and hybrid automatic repeat request (HARQ) information relatedto the DL-SCH. The PDCCH may carry a UL grant for reporting to the UEabout resource allocation of UL transmission. A physical control formatindicator channel (PCFICH) reports the number of OFDM symbols used forPDCCHs to the UE, and is transmitted in every subframe. A physicalhybrid ARQ indicator channel (PHICH) carries an HARQ acknowledgement(ACK)/non-acknowledgement (NACK) signal in response to UL transmission.A physical uplink control channel (PUCCH) carries UL control informationsuch as HARQ ACK/NACK for DL transmission, scheduling request, and CQI.A physical uplink shared channel (PUSCH) carries a UL-uplink sharedchannel (SCH).

FIG. 4 shows an example of a physical channel structure.

A physical channel consists of a plurality of subframes in time domainand a plurality of subcarriers in frequency domain. One subframeconsists of a plurality of symbols in the time domain. One subframeconsists of a plurality of resource blocks (RBs). One RB consists of aplurality of symbols and a plurality of subcarriers. In addition, eachsubframe may use specific subcarriers of specific symbols of acorresponding subframe for a PDCCH. For example, a first symbol of thesubframe may be used for the PDCCH. The PDCCH carries dynamic allocatedresources, such as a physical resource block (PRB) and modulation andcoding scheme (MCS). A transmission time interval (TTI) which is a unittime for data transmission may be equal to a length of one subframe. Thelength of one subframe may be 1 ms.

The transport channel is classified into a common transport channel anda dedicated transport channel according to whether the channel is sharedor not. A DL transport channel for transmitting data from the network tothe UE includes a broadcast channel (BCH) for transmitting systeminformation, a paging channel (PCH) for transmitting a paging message, aDL-SCH for transmitting user traffic or control signals, etc. The DL-SCHsupports HARQ, dynamic link adaptation by varying the modulation, codingand transmit power, and both dynamic and semi-static resourceallocation. The DL-SCH also may enable broadcast in the entire cell andthe use of beamforming. The system information carries one or moresystem information blocks. All system information blocks may betransmitted with the same periodicity. Traffic or control signals of amultimedia broadcast/multicast service (MBMS) may be transmitted throughthe DL-SCH or a multicast channel (MCH).

A UL transport channel for transmitting data from the UE to the networkincludes a random access channel (RACH) for transmitting an initialcontrol message, a UL-SCH for transmitting user traffic or controlsignals, etc. The UL-SCH supports HARQ and dynamic link adaptation byvarying the transmit power and potentially modulation and coding. TheUL-SCH also may enable the use of beamforming. The RACH is normally usedfor initial access to a cell.

A MAC layer belongs to the L2. The MAC layer provides services to aradio link control (RLC) layer, which is a higher layer of the MAClayer, via a logical channel. The MAC layer provides a function ofmapping multiple logical channels to multiple transport channels. TheMAC layer also provides a function of logical channel multiplexing bymapping multiple logical channels to a single transport channel. A MACsublayer provides data transfer services on logical channels.

The logical channels are classified into control channels fortransferring control plane information and traffic channels fortransferring user plane information, according to a type of transmittedinformation. That is, a set of logical channel types is defined fordifferent data transfer services offered by the MAC layer. The logicalchannels are located above the transport channel, and are mapped to thetransport channels.

The control channels are used for transfer of control plane informationonly. The control channels provided by the MAC layer include a broadcastcontrol channel (BCCH), a paging control channel (PCCH), a commoncontrol channel (CCCH), a multicast control channel (MCCH) and adedicated control channel (DCCH). The BCCH is a downlink channel forbroadcasting system control information. The PCCH is a downlink channelthat transfers paging information and is used when the network does notknow the location cell of a UE. The CCCH is used by UEs having no RRCconnection with the network. The MCCH is a point-to-multipoint downlinkchannel used for transmitting MBMS control information from the networkto a UE. The DCCH is a point-to-point bi-directional channel used by UEshaving an RRC connection that transmits dedicated control informationbetween a UE and the network.

Traffic channels are used for the transfer of user plane informationonly. The traffic channels provided by the MAC layer include a dedicatedtraffic channel (DTCH) and a multicast traffic channel (MTCH). The DTCHis a point-to-point channel, dedicated to one UE for the transfer ofuser information and can exist in both uplink and downlink. The MTCH isa point-to-multipoint downlink channel for transmitting traffic datafrom the network to the UE.

Uplink connections between logical channels and transport channelsinclude the DCCH that can be mapped to the UL-SCH, the DTCH that can bemapped to the UL-SCH and the CCCH that can be mapped to the UL-SCH.Downlink connections between logical channels and transport channelsinclude the BCCH that can be mapped to the BCH or DL-SCH, the PCCH thatcan be mapped to the PCH, the DCCH that can be mapped to the DL-SCH, andthe DTCH that can be mapped to the DL-SCH, the MCCH that can be mappedto the MCH, and the MTCH that can be mapped to the MCH.

An RLC layer belongs to the L2. The RLC layer provides a function ofadjusting a size of data, so as to be suitable for a lower layer totransmit the data, by concatenating and segmenting the data receivedfrom a higher layer in a radio section. In addition, to ensure a varietyof quality of service (QoS) required by a radio bearer (RB), the RLClayer provides three operation modes, i.e., a transparent mode (TM), anunacknowledged mode (UM), and an acknowledged mode (AM). The AM RLCprovides a retransmission function through an automatic repeat request(ARQ) for reliable data transmission. Meanwhile, a function of the RLClayer may be implemented with a functional block inside the MAC layer.In this case, the RLC layer may not exist.

A packet data convergence protocol (PDCP) layer belongs to the L2. ThePDCP layer provides a function of header compression function thatreduces unnecessary control information such that data being transmittedby employing IP packets, such as IPv4 or IPv6, can be efficientlytransmitted over a radio interface that has a relatively smallbandwidth. The header compression increases transmission efficiency inthe radio section by transmitting only necessary information in a headerof the data. In addition, the PDCP layer provides a function ofsecurity. The function of security includes ciphering which preventsinspection of third parties, and integrity protection which preventsdata manipulation of third parties.

A radio resource control (RRC) layer belongs to the L3. The RLC layer islocated at the lowest portion of the L3, and is only defined in thecontrol plane. The RRC layer takes a role of controlling a radioresource between the UE and the network. For this, the UE and thenetwork exchange an RRC message through the RRC layer. The RRC layercontrols logical channels, transport channels, and physical channels inrelation to the configuration, reconfiguration, and release of RBs. AnRB is a logical path provided by the L1 and L2 for data delivery betweenthe UE and the network. That is, the RB signifies a service provided theL2 for data transmission between the UE and E-UTRAN. The configurationof the RB implies a process for specifying a radio protocol layer andchannel properties to provide a particular service and for determiningrespective detailed parameters and operations. The RB is classified intotwo types, i.e., a signaling RB (SRB) and a data RB (DRB). The SRB isused as a path for transmitting an RRC message in the control plane. TheDRB is used as a path for transmitting user data in the user plane.

Referring to FIG. 2, the RLC and MAC layers (terminated in the eNB onthe network side) may perform functions such as scheduling, automaticrepeat request (ARQ), and hybrid automatic repeat request (HARQ). TheRRC layer (terminated in the eNB on the network side) may performfunctions such as broadcasting, paging, RRC connection management, RBcontrol, mobility functions, and UE measurement reporting andcontrolling. The NAS control protocol (terminated in the MME of gatewayon the network side) may perform functions such as a SAE bearermanagement, authentication, LTE_IDLE mobility handling, pagingorigination in LTE_IDLE, and security control for the signaling betweenthe gateway and UE.

Referring to FIG. 3, the RLC and MAC layers (terminated in the eNB onthe network side) may perform the same functions for the control plane.The PDCP layer (terminated in the eNB on the network side) may performthe user plane functions such as header compression, integrityprotection, and ciphering.

An RRC state indicates whether an RRC layer of the UE is logicallyconnected to an RRC layer of the E-UTRAN. The RRC state may be dividedinto two different states such as an RRC connected state and an RRC idlestate. When an RRC connection is established between the RRC layer ofthe UE and the RRC layer of the E-UTRAN, the UE is in RRC_CONNECTED, andotherwise the UE is in RRC_IDLE. Since the UE in RRC_CONNECTED has theRRC connection established with the E-UTRAN, the E-UTRAN may recognizethe existence of the UE in RRC_CONNECTED and may effectively control theUE. Meanwhile, the UE in RRC_IDLE may not be recognized by the E-UTRAN,and a CN manages the UE in unit of a TA which is a larger area than acell. That is, only the existence of the UE in RRC_IDLE is recognized inunit of a large area, and the UE must transition to RRC_CONNECTED toreceive a typical mobile communication service such as voice or datacommunication.

In RRC_IDLE state, the UE may receive broadcasts of system informationand paging information while the UE specifies a discontinuous reception(DRX) configured by NAS, and the UE has been allocated an identification(ID) which uniquely identifies the UE in a tracking area and may performpublic land mobile network (PLMN) selection and cell re-selection. Also,in RRC_IDLE state, no RRC context is stored in the eNB.

In RRC_CONNECTED state, the UE has an E-UTRAN RRC connection and acontext in the E-UTRAN, such that transmitting and/or receiving datato/from the eNB becomes possible. Also, the UE can report channelquality information and feedback information to the eNB. InRRC_CONNECTED state, the E-UTRAN knows the cell to which the UE belongs.Therefore, the network can transmit and/or receive data to/from UE, thenetwork can control mobility (handover and inter-radio accesstechnologies (RAT) cell change order to GSM EDGE radio access network(GERAN) with network assisted cell change (NACC)) of the UE, and thenetwork can perform cell measurements for a neighboring cell.

In RRC_IDLE state, the UE specifies the paging DRX cycle. Specifically,the UE monitors a paging signal at a specific paging occasion of everyUE specific paging DRX cycle. The paging occasion is a time intervalduring which a paging signal is transmitted. The UE has its own pagingoccasion.

A paging message is transmitted over all cells belonging to the sametracking area. If the UE moves from one TA to another TA, the UE willsend a tracking area update (TAU) message to the network to update itslocation.

When the user initially powers on the UE, the UE first searches for aproper cell and then remains in RRC_IDLE in the cell. When there is aneed to establish an RRC connection, the UE which remains in RRC_IDLEestablishes the RRC connection with the RRC of the E-UTRAN through anRRC connection procedure and then may transition to RRC_CONNECTED. TheUE which remains in RRC_IDLE may need to establish the RRC connectionwith the E-UTRAN when uplink data transmission is necessary due to auser's call attempt or the like or when there is a need to transmit aresponse message upon receiving a paging message from the E-UTRAN.

It is known that different cause values may be mapped o the signaturesequence used to transmit messages between a UE and eNB and that eitherchannel quality indicator (CQI) or path loss and cause or message sizeare candidates for inclusion in the initial preamble.

When a UE wishes to access the network and determines a message to betransmitted, the message may be linked to a purpose and a cause valuemay be determined. The size of the ideal message may be also bedetermined by identifying all optional information and differentalternative sizes, such as by removing optional information, or analternative scheduling request message may be used.

The UE acquires necessary information for the transmission of thepreamble, UL interference, pilot transmit power and requiredsignal-to-noise ratio (SNR) for the preamble detection at the receiveror combinations thereof. This information must allow the calculation ofthe initial transmit power of the preamble. It is beneficial to transmitthe UL message in the vicinity of the preamble from a frequency point ofview in order to ensure that the same channel is used for thetransmission of the message.

The UE should take into account the UL interference and the UL path lossin order to ensure that the network receives the preamble with a minimumSNR. The UL interference can be determined only in the eNB, andtherefore, must be broadcast by the eNB and received by the UE prior tothe transmission of the preamble. The UL path loss can be considered tobe similar to the DL path loss and can be estimated by the UE from thereceived RX signal strength when the transmit power of some pilotsequence of the cell is known to the UE.

The required UL SNR for the detection of the preamble would typicallydepend on the eNB configuration, such as a number of Rx antennas andreceiver performance. There may be advantages to transmit the ratherstatic transmit power of the pilot and the necessary UL SNR separatelyfrom the varying UL interference and possibly the power offset requiredbetween the preamble and the message.

The initial transmission power of the preamble can be roughly calculatedaccording to the following formula:Transmit power=TransmitPilot−RxPilot+ULInterference+Offset+SNRRequired

Therefore, any combination of SNRRequired, ULInterference, TransmitPilotand Offset can be broadcast. In principle, only one value must bebroadcast. This is essentially in current UMTS systems, although the ULinterference in 3GPP LTE will mainly be neighboring cell interferencethat is probably more constant than in UMTS system.

The UE determines the initial UL transit power for the transmission ofthe preamble as explained above. The receiver in the eNB is able toestimate the absolute received power as well as the relative receivedpower compared to the interference in the cell. The eNB will consider apreamble detected if the received signal power compared to theinterference is above an eNB known threshold.

The UE performs power ramping in order to ensure that a UE can bedetected even if the initially estimated transmission power of thepreamble is not adequate. Another preamble will most likely betransmitted if no ACK or NACK is received by the UE before the nextrandom access attempt. The transmit power of the preamble can beincreased, and/or the preamble can be transmitted on a different ULfrequency in order to increase the probability of detection. Therefore,the actual transmit power of the preamble that will be detected does notnecessarily correspond to the initial transmit power of the preamble asinitially calculated by the UE.

The UE must determine the possible UL transport format. The transportformat, which may include MCS and a number of resource blocks thatshould be used by the UE, depends mainly on two parameters, specificallythe SNR at the eNB and the required size of the message to betransmitted.

In practice, a maximum UE message size, or payload, and a requiredminimum SNR correspond to each transport format. In UMTS, the UEdetermines before the transmission of the preamble whether a transportformat can be chosen for the transmission according to the estimatedinitial preamble transmit power, the required offset between preambleand the transport block, the maximum allowed or available UE transmitpower, a fixed offset and additional margin. The preamble in UMTS neednot contain any information regarding the transport format selected bythe EU since the network does not need to reserve time and frequencyresources and, therefore, the transport format is indicated togetherwith the transmitted message.

The eNB must be aware of the size of the message that the UE intends totransmit and the SNR achievable by the UE in order to select the correcttransport format upon reception of the preamble and then reserve thenecessary time and frequency resources. Therefore, the eNB cannotestimate the SNR achievable by the EU according to the received preamblebecause the UE transmit power compared to the maximum allowed orpossible UE transmit power is not known to the eNB, given that the UEwill most likely consider the measured path loss in the DL or someequivalent measure for the determination of the initial preambletransmission power.

The eNB could calculate a difference between the path loss estimated inthe DL compared and the path loss of the UL. However, this calculationis not possible if power ramping is used and the UE transmit power forthe preamble does not correspond to the initially calculated UE transmitpower. Furthermore, the precision of the actual UE transmit power andthe transmit power at which the UE is intended to transmit is very low.Therefore, it has been proposed to code the path loss or CQI estimationof the downlink and the message size or the cause value In the UL in thesignature.

Carrier aggregation (CA) is described. It may be referred to Section 5.5of 3GPP TS 36.300 V11.4.0 (December 2012).

FIG. 5 shows an example of a carrier aggregation of 3GPP LTE-A.Referring to FIG. 5, each component carrier (CC) has a bandwidth of 20MHz, which is a bandwidth of 3GPP LTE. Up to 5 CCs may be aggregated, somaximum bandwidth of 100 MHz may be configured.

When the CA is configured, the UE only has one RRC connection with thenetwork. At RRC connection establishment/re-establishment, one servingcell provides the security input (one E-UTRAN cell global identifier(ECGI), one physical cell identifier (PCI) and one absoluteradio-frequency channel number (ARFCN)) and the NAS mobility information(e.g., tracking area identity (TAI)) similarly as in Rel-8/9. This cellis referred to as the PCell. In the downlink, the carrier correspondingto the primary serving cell (PCell) is the downlink primary componentcarrier (DL PCC) while in the uplink it is the uplink primary componentcarrier (UL PCC).

Depending on UE capabilities, secondary serving cells (SCells) can beconfigured to form together with the PCell a set of serving cells. Inthe downlink, the carrier corresponding to a SCell is a downlinksecondary component carrier (DL SCC) while in the uplink it is an uplinksecondary component carrier (UL SCC).

The configured set of serving cells for a UE therefore always consistsof one PCell and one or more SCells:

-   -   For each SCell the usage of uplink resources by the UE in        addition to the downlink ones is configurable (the number of DL        SCCs configured is therefore always larger or equal to the        number of UL SCCs and no SCell can be configured for usage of        uplink resources only);    -   The number of serving cells that can be configured depends on        the aggregation capability of the UE;    -   PCell can only be changed with handover procedure (i.e., with        security key change and RACH procedure);    -   PCell is used for transmission of PUCCH;    -   PCell is used for random access procedure;    -   Unlike SCells, PCell cannot be de-activated;    -   Re-establishment is triggered when PCell experiences radio link        failure (RLF), not when SCells experience RLF;    -   NAS information is taken from PCell.

The reconfiguration, addition and removal of SCells can be performed byRRC. At intra-LTE handover, RRC can also add, remove, or reconfigureSCells for usage with the target PCell. When adding a new SCell,dedicated RRC signaling is used for sending the system information ofthe SCell required for transmission/reception (similarly as in Rel-8/9for handover).

FIG. 6 shows an example of a structure of DL layer 2 when carrieraggregation is used. FIG. 7 shows an example of a structure of UL layer2 when carrier aggregation is used. The carrier aggregation may affect aMAC layer of the L2. For example, since the carrier aggregation uses aplurality of CCs, and each hybrid automatic repeat request (HARQ) entitymanages each CC, the MAC layer of 3GPP LTE-A using the CA shall performoperations related to a plurality of HARQ entities. Further, each HARQentity processes a transport block independently. Therefore, when the CAis used, a plurality of transport blocks may be transmitted or receivedat the same time through a plurality of CCs.

In Rel-10, for the uplink, the focus is laid on the support ofintra-band carrier aggregations. For the downlink, all scenarios shouldbe supported in Rel-10.

FIG. 8 shows an example of a potential deployment scenario for CA.Referring to FIG. 8, F1 and F2 cells are co-located and overlaid,providing nearly the same coverage. Both layers provide sufficientcoverage and mobility can be supported on both layers. Likely scenariois when F1 and F2 are of the same band, e.g., 2 GHz, 800 MHz, etc. It isexpected that aggregation is possible between overlaid F1 and F2 cells.

FIG. 9 shows another example of a potential deployment scenario for CA.F1 and F2 cells are co-located and overlaid, but F2 has smaller coveragedue to larger path loss. Only F1 provides sufficient coverage and F2 isused to improve throughput. Mobility is performed based on F1 coverage.Likely scenario when F1 and F2 are of different bands, e.g., F1={800MHz, 2 GHz} and F2={3.5 GHz}, etc. It is expected that aggregation ispossible between overlaid F1 and F2 cells.

FIG. 10 shows another example of a potential deployment scenario for CA.F1 and F2 cells are co-located but F2 antennas are directed to the cellboundaries of F1 so that cell edge throughput is increased. F1 providessufficient coverage but F2 potentially has holes, e.g., due to largerpath loss. Mobility is based on F1 coverage. Likely scenario is when F1and F2 are of different bands, e.g., F1={800 MHz, 2 GHz} and F2={3.5GHz}, etc. It is expected that F1 and F2 cells of the same eNB can beaggregated where coverage overlaps.

FIG. 11 shows another example of a potential deployment scenario for CA.F1 provides macro coverage and on F2 remote radio heads (RRHs) are usedto improve throughput at hot spots. Mobility is performed based on F1coverage. Likely scenario is when F1 and F2 are of different bands,e.g., F1={800 MHz, 2 GHz} and F2={3.5 GHz}, etc. It is expected that F2RRHs cells can be aggregated with the underlying F1 macro cells.

FIG. 12 shows another example of a potential deployment scenario for CA.It is similar to the scenario described in FIG. 9, but frequencyselective repeaters are deployed so that coverage is extended for one ofthe carrier frequencies. It is expected that F1 and F2 cells of the sameeNB can be aggregated where coverage overlaps.

Activation/deactivation of SCells is described. It may be referred toSection 5.13 of 3GPP TS 36.321 V11.1.0 (December 2012).

If the UE is configured with one or more SCells, the network mayactivate and deactivate the configured SCells. The PCell is alwaysactivated. The network activates and deactivates the SCell(s) by sendingthe activation/deactivation MAC control element. Furthermore, the UEmaintains a sCellDeactivationTimer timer per configured SCell anddeactivates the associated SCell upon its expiry. The same initial timervalue applies to each instance of the sCellDeactivationTimer and it isconfigured by RRC. The configured SCells are initially deactivated uponaddition and after a handover.

The UE shall for each TTI and for each configured SCell:

1> if the UE receives an Activation/Deactivation MAC control element inthis TTI activating the SCell, the UE shall in the TTI according to thetiming:

2> activate the SCell; i.e., apply normal SCell operation including:

3> SRS transmissions on the SCell;

3> CQI/PMI/RI/PTI reporting for the SCell;

3> PDCCH monitoring on the SCell;

3> PDCCH monitoring for the SCell

2> start or restart the sCellDeactivationTimer associated with theSCell;

1> else, if the UE receives an Activation/Deactivation MAC controlelement in this TTI deactivating the SCell; or

1> if the sCellDeactivationTimer associated with the activated SCellexpires in this TTI:

2> in the TTI according to the timing:

3> deactivate the SCell;

3> stop the sCellDeactivationTimer associated with the SCell;

3> flush all HARQ buffers associated with the SCell.

1> if PDCCH on the activated SCell indicates an uplink grant or downlinkassignment; or

1> if PDCCH on the Serving Cell scheduling the activated SCell indicatesan uplink grant or a downlink assignment for the activated SCell:

2> restart the sCellDeactivationTimer associated with the SCell;

1> if the SCell is deactivated:

2> not transmit SRS on the SCell;

2> not report CQI/PMI/RI/PTI for the SCell;

2> not transmit on UL-SCH on the SCell;

2> not transmit on RACH on the SCell;

2> not monitor the PDCCH on the SCell;

2> not monitor the PDCCH for the SCell.

When SCell is deactivated, the ongoing random access procedure on theSCell, if any, is aborted.

The activation/deactivation MAC control element is identified by a MACPDU subheader with logical channel ID (LCID). It has a fixed size andconsists of a single octet containing seven C-fields and one R-field.The activation/deactivation MAC control element is defined as follows.

-   -   C_(i): if there is a SCell configured with SCellIndex i, this        field indicates the activation/deactivation status of the SCell        with SCellIndex i, else the UE shall ignore the C_(i) field. The        C_(i) field is set to “1” to indicate that the SCell with        SCellIndex i shall be activated. The C_(i) field is set to “0”        to indicate that the SCell with SCellIndex i shall be        deactivated;    -   R: Reserved bit, set to “0”.

An RRC connection reconfiguration is described. It may be referred toSection 5.3.5 of 3GPP TS 36.331 V11.2.0 (December 2012).

FIG. 13 shows an RRC connection reconfiguration procedure. The purposeof the RRC connection reconfiguration is to modify an RRC connection,e.g., to establish/modify/release RBs, to perform handover, tosetup/modify/release measurements, to add/modify/release SCells. As partof the procedure, NAS dedicated information may be transferred fromE-UTRAN to the UE.

FIG. 13-(a) shows a successful RRC connection reconfiguration procedure.In step S50, the E-UTRAN transmits the RRCConnectionReconfigurationmessage. In step S51, the UE transmits theRRCConnectionReconfigurationComplete message.

FIG. 13-(b) shows a failed RRC connection reconfiguration procedure. Instep S60, the E-UTRAN transmits the RRCConnectionReconfigurationmessage. In step S61, the UE and E-TURAN performs an RRC connectionre-establishment procedure.

E-UTRAN may initiate the RRC connection reconfiguration procedure to aUE in RRC_CONNECTED. E-UTRAN applies the procedure as follows:

-   -   the mobilityControlInfo is included only when AS-security has        been activated, and SRB2 with at least one DRB are setup and not        suspended;]    -   the establishment of RBs (other than SRB1, that is established        during RRC connection establishment) is included only when AS        security has been activated;    -   the addition of SCells is performed only when AS security has        been activated;

If the RRCConnectionReconfiguration message does not include themobilityControlInfo and the UE is able to comply with the configurationincluded in this message, the UE shall:

1> if this is the first RRCConnectionReconfiguration message aftersuccessful completion of the RRC Connection Re-establishment procedure:

2> re-establish PDCP for SRB2 and for all DRBs that are established, ifany;

2> re-establish RLC for SRB2 and for all DRBs that are established, ifany;

2> if the RRCConnectionReconfiguration message includes the fullConfig:

3> perform the radio configuration procedure;

2> if the RRCConnectionReconfiguration message includes theradioResourceConfigDedicaled:

3> perform the radio resource configuration procedure;

2> resume SRB2 and all DRBs that are suspended, if any;

1> else:

2> if the RRCConnectionReconfiguration message includes theradioResourceConfigDedicated:

3> perform the radio resource configuration procedure;

1> if the received RRCConnectionReconfiguration includes thesCellToReleaseList:

2> perform SCell release;

1> if the received RRCConnectionReconfiguration includes thesCellToAddModList:

2> perform SCell addition or modification;

1> if the RRCConnectionReconfiguration message includes thededicatedInfoNASList:

2> forward each element of the dedicatedInfoNASList to upper layers inthe same order as listed;

1> if the RRCConnectionReconfiguration message includes the measConfig:

2> perform the measurement configuration procedure;

1> perform the measurement identity autonomous removal;

1> if the RRCConnectionReconfiguration message includes thereportProximityConfig:

2> perform the proximity indication in accordance with the receivedreportProximityConfig;

1> submit the RRCConnectionReconfigurationComplete message to lowerlayers for transmission using the new configuration, upon which theprocedure ends;

If the RRCConnectionReconfiguration message includes themobilityControlInfo and the UE is able to comply with the configurationincluded in this message, the UE shall:

1> stop timer T310, if running;

1> start timer T304 with the timer value set to t304, as included in themobilityControlInfo;

1> if the carrierFreq is included:

2> consider the target PCell to be one on the frequency indicated by thecarrierFreq with a physical cell identity indicated by thelarge/PhysCellId;

1> else:

2> consider the target PCell to be one on the frequency of the sourcePCell with a physical cell identity indicated by the targetPhysCellId;

1> start synchronising to the DL of the target PCell;

1> reset MAC;

1> re-establish PDCP for all RBs that are established;

1> re-establish RLC for all RBs that are established;

1> configure lower layers to consider the SCell(s), if configured, to bein deactivated state;

1> apply the value of the newUE-Identity as the C-RNTI;

1> if the RRCConnectionReconfiguration message includes the fullConfig:

2> perform the radio configuration procedure;

1> configure lower layers in accordance with the receivedradioResourceConfigCommon;

1> configure lower layers in accordance with any additional fields, notcovered in the previous, if included in the receivedmobilityControlInfo;

1> if the RRCConnectionReconfiguration message includes theradioResourceConfigDedicated:

2> perform the radio resource configuration procedure;

1> if the keyChangeIndicator received in the securityConfigHO is set toTRUE:

2> update the K_(eNB) key based on the fresh K_(ASME) key taken into usewith the previous successful NAS SMC procedure;

1> else:

2> update the K_(eNB) key based on the current K_(eNB) or the NH, usingthe nextHopChainingCount value indicated in the securityConfigHO;

1> store the nextHopChainingCount value;

1> if the securayAlgorithmConfig is included in the securityConfigHO:

2> derive the K_(RRCint) key associated with the integrityProtAlgorithm;

2> if connected as an RN:

3> derive the K_(UPint) key associated with the integrityProtAlgorithm;

2> derive the K_(RRCenc) key and the K_(UPenc) key associated with thecipheringAlgorithm;

1> else:

2> derive the K_(RRCint) key associated with the current integrityalgorithm;

2> if connected as an RN:

3> derive the K_(UPint) key associated with the current integrityalgorithm;

2> derive the K_(RRCene) key and the K_(UPenc) key associated with thecurrent ciphering algorithm;

1> configure lower layers to apply the integrity protection algorithmand the K_(RRCint) key, i.e. the integrity protection configurationshall be applied to all subsequent messages received and sent by the UE,including the message used to indicate the successful completion of theprocedure;

1> configure lower layers to apply the ciphering algorithm, theK_(RRCenc) key and the K_(UPenc) key, i.e. the ciphering configurationshall be applied to all subsequent messages received and sent by the UE,including the message used to indicate the successful completion of theprocedure;

1> if connected as an RN:

2> configure lower layers to apply the integrity protection algorithmand the K_(UPint) key, for current or subsequently established DRBs thatare configured to apply integrity protection, if any;

1> if the received RRCConnectionReconfiguration includes thesCellToReleaseList:

2> perform SCell release;

1> if the received RRCConnectionReconfiguration includes thesCellToAddModList:

2> perform SCell addition or modification;

1> perform the measurement related actions;

1> if the RRCConnectionReconfiguration message includes the measConfig:

2> perform the measurement configuration procedure;

1> perform the measurement identity autonomous removal;

1> release reportProximityConfig and clear any associated proximitystatus reporting timer;

1> if the RRCConnectionReconfiguration message includes thereportProximityConfig:

2> perform the proximity indication in accordance with the receivedreportProximilyConfig;

1> set the content of RRCConnectionReconfigurationComplete message asfollows:

2> if the UE has radio link failure or handover failure informationavailable in VarRLF-Report and plmn-Identity stored in VarRLF-Report isequal to the RPLMN:

3> include rlf-InfoAvailable;

2> if the UE has logged measurements available for E-UTRA andplum-Identity stored in VarLogMeasReport is equal to the RPLMN:

3> include the logMeasAvailable;

1> submit the RRCConnectionReconfigurationComplete message to lowerlayers for transmission;

1> if MAC successfully completes the random access procedure:

2> stop timer T304;

2> apply the parts of the CQI reporting configuration, the schedulingrequest configuration and the sounding RS configuration that do notrequire the UE to know the SFN of the target PCell, if any;

2> apply the parts of the measurement and the radio resourceconfiguration that require the UE to know the SFN of the target PCell(e.g. measurement gaps, periodic CQI reporting, scheduling requestconfiguration, sounding RS configuration), if any, upon acquiring theSFN of the target PCell;

2> the procedure ends;

SCell addition/modification is described. It may be referred to Section5.3.10.3b of 3GPP TS 36.331 V11.2.0 (December 2012). The UE shall:

1> for each sCellIndex value included in the sCellToAddModList that isnot part of the current UE configuration (SCell addition):

2> add the SCell, corresponding to the cellIdentification, in accordancewith the received radioResourceConfigCommonSCell andradioResourceConfigDedicatedSCell;

2> configure lower layers to consider the SCell to be in deactivatedstate;

1> for each sCellIndex value included in the sCellToAddModList that ispart of the current UE configuration (SCell modification):

2> modify the SCell configuration in accordance with the receivedradioResourceConfigDedicatedSCell;

Small cell enhancement is described. It may be referred to 3GPP TR36.932 V12.0.0 (December 2012).

FIG. 14 shows deployment scenarios of small cells with/without macrocoverage. Small cell enhancement should target both with and withoutmacro coverage, both outdoor and indoor small cell deployments and bothideal and non-ideal backhaul. Both sparse and dense small celldeployments should be considered.

Referring to FIG. 14, small cell enhancement should target thedeployment scenario in which small cell nodes are deployed under thecoverage of one or more than one overlaid E-UTRAN macro-cell layer(s) inorder to boost the capacity of already deployed cellular network. Twoscenarios can be considered:

-   -   where the UE is in coverage of both the macro cell and the small        cell simultaneously    -   where the UE is not in coverage of both the macro cell and the        small cell simultaneously.

Also, the deployment scenario where small cell nodes are not deployedunder the coverage of one or more overlaid E-UTRAN macro-cell layer(s)may be considered.

FIG. 15 shows an example of dual connectivity to a macro cell and smallcell.

Referring to FIG. 15, an MeNB stands for a master eNB (or, a macro celleNB), and an SeNB stands for a secondary eNB (or, a small cell eNB). TheUE has a connection with the MeNB in frequency f1. In dual connectivity,the MeNB controls the macro cell, and is the eNB which terminates atleast S1-MME and therefore act as mobility anchor towards the CN. Also,the UE has a connection with the SeNB in frequency f2. In dualconnectivity, the SeNB controls one or more small cells, and is the eNBproviding additional radio resources for the UE, which is not the MeNB.Accordingly, the UE may receive control signaling from the MeNB, and mayreceive data from the SeNB. The interface between the MeNB and SeNB iscalled an Xn interface. The Xn interface is assumed to be non-idealbackhaul. For example, delay in the Xn interface could be up to 60 ms.

FIG. 16 shows an example of protocol architecture supporting dualconnectivity.

Referring to FIG. 16, the SeNB is responsible for transmitting besteffort (BE) type traffic, while the MeNB is responsible for transmittingother types of traffic such as voice over VoIP, streaming data, orsignaling data. That is, the SeNB is responsible for transmittingBE-DRBs, and the MeNB is responsible for transmitting other RB, such asSRBs and other DRBs. In the architecture described in FIG. 16, PDCP andRLC entities are located in different network nodes. That is, the PDCPentity is located in the MeNB and the RLC entity is located in the SeNB.In the UE side, the protocol architecture is same as prior art exceptthat the MAC entity is setup for each eNB (i.e., MeNB and SeNB).Meanwhile, the protocol architecture described in FIG. 16 is just anexample, and various protocol architectures may be used.

Conventionally, when the UE is configured with a new SCell by an RRCconnection reconfiguration message, since the initial state of a SCellis defined as deactivated state, the UE shall considers the new SCell tobe in deactivated state. Consequently, for use of the SCell, the eNBtransmits a SCell activation/deactivation command indicating activationfor the SCell to the UE. Upon receiving the SCellactivation/deactivation command, the UE activates the SCell. The SCellis available for communication between the UE and eNB after SCellactivation is performed.

However, always putting the added SCell in deactivated state may not beoptimal because of following reasons:

-   -   If the eNB intends to add the SCell so that it can use the SCell        immediately, the additional step for activating the SCell causes        delay.    -   There is no means to use the SCell unless SCell        activation/deactivation is implemented in the eNB and UE. For        example, the SCell activation/deactivation command is a        mandatory feature that should be supported in the eNB and UE.        Therefore, it increases cost.

To solve the problem described above, a method for indicating an initialstate of a SCell, and configuring the SCell based on the initial stateof the SCell according to an embodiment of the present invention isdescribed. According to an embodiment of the present invention, when aSCell is added, an indication is used to indicate an initial state ofthe SCell. The initial state of the SCell may be either an activatedstate or deactivated state. When the SCell is added or modified by anRRC connection reconfiguration message, the eNB transmits the indicationto the UE.

The indication may be defined per UE or per cell. If the indication isdefined per UE, the initial state of the SCell indicated by theindication may be applied to all SCells. For example, if the indicationindicates that the initial state of the SCell is the activated state,the initial state of SCells following the indication is set to theactivated state. That is, if the initial state of the SCell is set tothe activated state by the indication, when the SCells are added, the UEconsiders the SCells to be in the activated state.

If the indication is defined per cell, the initial state of the SCellindicated by the indication may be applied only to the associated SCell.Therefore, the indication should be indicated for each SCell. Forexample, when two SCells (A and B) are added, if the indication for theSCell A indicates the initial state of the SCell A is the activatedstate and the indication for the SCell B indicates that the initialstate of the SCell B is the deactivate state, the UE consider the SCellA to be in the activated state and the SCell B to be in the deactivatedstate.

The indication may be indicated to the UE explicitly or implicitly. Ifthe explicit indication is used, the indication may include informationon whether the initial state of the SCell is the activate state or thedeactivate state. If the implicit indication is used, the indication mayinclude only information that the initial state of the SCell is theactivation state. That is, when the eNB wants the deactivate state asthe initial state of the SCell, the eNB may not transmit the indicationto the UE. So, because the indication is not explicitly indicated to theUE, the UE assumes that the initial state of the SCell is thedeactivated state.

Further, the indication may change the state of the SCell currentlyconfigured to the UE. If the UE receives the indication from the eNBthat the initial state is the deactivated state for the SCell alreadyconfigured to the UE, and currently, the state of the SCell is theactivated state, the UE may deactivate the SCell and performscorresponding operations for the deactivated SCell. If the indication isdefined per UE, when the UE receives the indication that the state ofthe SCell is the deactivated state, the UE may deactivate all SCells.

FIG. 17 shows an example of a SCell addition with an indication of aninitial state according to an embodiment of the present invention.

In step S100, the UE is configured with a SCell1. Also, the UE receivesan indication of an initial state of the SCell 1. In this example, it isassumed that the initial state of the SCell 1 is the activated state.

In step S110, upon receiving the indication of the initial state of theSCell 1, the UE consider the SCell 1 to be in the activated state.

In step S120, therefore, the UE can receive/transmit data on the SCell 1without an additional SCell activation command.

In step S130, the UE is further configured with a SCell 2. The UEreceives an indication of an initial state of the SCell 2 as well. Inthis example, it is assumed that the initial state of the SCell 2 is thedeactivated state.

In step S140, upon receiving the indication of the initial state of theSCell 2, the UE consider the SCell 2 to be in the deactivated state.

In step S150, the UE receives a SCell 2 activation command. Uponreceiving the SCell 2 activation command, then the UE activates SCell2.

In step S160, the UE can now receive/transmit data on the SCell 2.

FIG. 18 shows an example of a method for configuring a SCell accordingto an embodiment of the present invention.

In step S200, the UE receives an RRC message which includes aconfiguration for a SCell and an indication of an initial state of theSCell. The initial state of the SCell is set to either one of anactivated state and deactivated state. The indication may be receivedvia an RRC connection reconfiguration message. The indication may bedefined per UE or per cell.

In step S210, the UE configures the SCell based on the configuration andthe initial state of the SCell. If the initial state of the SCell is setto the activated state, the UE may transmit or receive data on the SCellwithout an additional activation command. If the initial state of theSCell is set to the deactivated state, the UE may receive an activationcommand for the SCell, and may activate the SCell according to theactivation command.

FIG. 19 shows a wireless communication system to implement an embodimentof the present invention.

An eNB 800 may include a processor 810, a memory 820 and a radiofrequency (RF) unit 830. The processor 810 may be configured toimplement proposed functions, procedures and/or methods described inthis description. Layers of the radio interface protocol may beimplemented in the processor 810. The memory 820 is operatively coupledwith the processor 810 and stores a variety of information to operatethe processor 810. The RF unit 830 is operatively coupled with theprocessor 810, and transmits and/or receives a radio signal.

A UE 900 may include a processor 910, a memory 920 and a RF unit 930.The processor 910 may be configured to implement proposed functions,procedures and/or methods described in this description. Layers of theradio interface protocol may be implemented in the processor 910. Thememory 920 is operatively coupled with the processor 910 and stores avariety of information to operate the processor 910. The RF unit 930 isoperatively coupled with the processor 910, and transmits and/orreceives a radio signal.

The processors 810, 910 may include application-specific integratedcircuit (ASIC), other chipset, logic circuit and/or data processingdevice. The memories 820, 920 may include read-only memory (ROM), randomaccess memory (RAM), flash memory, memory card, storage medium and/orother storage device. The RF units 830, 930 may include basebandcircuitry to process radio frequency signals. When the embodiments areimplemented in software, the techniques described herein can beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. The modules can be stored inmemories 820, 920 and executed by processors 810, 910. The memories 820,920 can be implemented within the processors 810, 910 or external to theprocessors 810, 910 in which case those can be communicatively coupledto the processors 810, 910 via various means as is known in the art.

In view of the exemplary systems described herein, methodologies thatmay be implemented in accordance with the disclosed subject matter havebeen described with reference to several flow diagrams. While forpurposed of simplicity, the methodologies are shown and described as aseries of steps or blocks, it is to be understood and appreciated thatthe claimed subject matter is not limited by the order of the steps orblocks, as some steps may occur in different orders or concurrently withother steps from what is depicted and described herein. Moreover, oneskilled in the art would understand that the steps illustrated in theflow diagram are not exclusive and other steps may be included or one ormore of the steps in the example flow diagram may be deleted withoutaffecting the scope and spirit of the present disclosure.

What is claimed is:
 1. A method for configuring, by a user equipment(UE), a cell in a wireless communication system, the method comprising:receiving, from a base station, a radio resource control (RRC)connection reconfiguration message including a secondary cell (SCell)configuration for configuring a new SCell; configuring the new SCellbased on the SCell configuration; when the RRC connectionreconfiguration message further includes initial state information ofthe new SCell indicating an initial state of the new SCell is anactivated state: configuring the new SCell based on the new SCell beingin the activated state, and transmitting or receiving data via the newSCell which is activated upon configuring the new SCell; and when theRRC connection reconfiguration message does not include the initialstate information of the new SCell: configuring the new SCell based onthe new SCell being in a deactivated state, receiving information foractivating the new SCell, activating the new SCell based on theinformation, and transmitting or receiving data via the new SCell whichhas been activated based on the information.
 2. The method of claim 1,wherein the initial state information is configured for the new SCell.3. The method of claim 1, wherein the initial state information isdefined per UE or per cell.
 4. A user equipment (UE) in a wirelesscommunication system, the UE comprising: a memory; a transceiver; and aprocessor, connected with the memory and the transceiver, that: controlsthe transceiver to receive, from a base station, a radio resourcecontrol (RRC) connection reconfiguration message including a secondarycell (SCell) configuration for configuring a new SCell; configures thenew SCell based on the SCell configuration; when the RRC connectionreconfiguration message further includes initial state information ofthe new SCell indicating an initial state of the new SCell is anactivated state: configures the new SCell based on the new SCell beingin the activated state, and controls the transceiver to transmit orreceive data via the new SCell which is activated upon configuring thenew SCell; and when the RRC connection reconfiguration message does notinclude the initial state information of the new SCell: configures thenew SCell based on the new SCell being in a deactivated state, controlsthe transceiver to receive information for activating the new SCell,activates the new SCell based on the information, and controls thetransceiver to transmit or receive data via the new SCell which has beenactivated based on the information.
 5. The UE of claim 4, wherein theinitial state information is configured for the new SCell.
 6. The UE ofclaim 4, wherein the initial state information is defined per UE or percell.